diff --git a/.github/workflows/aot.yml b/.github/workflows/aot.yml
index ea23d765..b1ce838a 100644
--- a/.github/workflows/aot.yml
+++ b/.github/workflows/aot.yml
@@ -17,7 +17,10 @@ jobs:
           - ubuntu-latest
         architecture: [x64]
         python-version: ['3.8']
-        julia-version: ['1.5', 'nightly']
+        julia-version:
+          - '1.5'
+          - '~1.7.0-rc1'
+          # - 'nightly'  # TODO: reenable
       fail-fast: false
     env:
       PYTHON: python${{ matrix.python-version }}
@@ -34,6 +37,9 @@ jobs:
           architecture: ${{ matrix.architecture }}
       - run: python --version
       - run: python -m pip install --user numpy
+      - name: Install libpython2.7 for `find_libpython` test
+        run: sudo apt-get install python2.7-dev
+        if: ${{ matrix.python-version != '2.7' && matrix.os == 'ubuntu-latest' }}
       - name: Setup julia
         uses: julia-actions/setup-julia@v1
         with:
diff --git a/.github/workflows/conda.yml b/.github/workflows/conda.yml
index caa1149a..e16eb193 100644
--- a/.github/workflows/conda.yml
+++ b/.github/workflows/conda.yml
@@ -32,6 +32,9 @@ jobs:
       ${{ matrix.os }} ${{ matrix.architecture }}
     steps:
       - uses: actions/checkout@v1
+      - name: Install libpython2.7 for `find_libpython` test
+        run: sudo apt-get install python2.7-dev
+        if: ${{ matrix.python-version != '2.7' && matrix.os == 'ubuntu-latest' }}
       - name: Setup julia
         uses: julia-actions/setup-julia@v1
         with:
diff --git a/.github/workflows/system.yml b/.github/workflows/system.yml
index e52ef8de..8caae1a1 100644
--- a/.github/workflows/system.yml
+++ b/.github/workflows/system.yml
@@ -18,13 +18,15 @@ jobs:
           - macos-latest
           - windows-latest
         architecture: [x64]
-        python-version: ['2.7', '3.8']
+        python-version: ['3.8']
         julia-version: ['1.0', '1.5', 'nightly']
         include:
+          # 32 bit Windows:
           - os: windows-latest
             architecture: x86
             python-version: '3.8'
             julia-version: '1.5'
+          # Sweep julia-version only on Ubuntu:
           - os: ubuntu-latest
             architecture: x64
             python-version: '3.7'
@@ -37,6 +39,16 @@ jobs:
             architecture: x64
             python-version: '3.8'
             julia-version: '1.3'
+          # Test Python 2.7 only with a few combinations (TODO: drop 2.7).
+          # Note that it does not work in macOS:
+          - os: ubuntu-latest
+            architecture: x64
+            python-version: '2.7'
+            julia-version: '1.5'
+          - os: windows-latest
+            architecture: x64
+            python-version: '2.7'
+            julia-version: '1.5'
       fail-fast: false
     name: Test
       Julia ${{ matrix.julia-version }}
@@ -56,6 +68,9 @@ jobs:
         if: ${{ matrix.python-version != '2.7' }}
       - run: virtualenv --version
         if: ${{ matrix.python-version != '2.7' }}
+      - name: Install libpython2.7 for `find_libpython` test
+        run: sudo apt-get install python2.7-dev
+        if: ${{ matrix.python-version != '2.7' && matrix.os == 'ubuntu-latest' }}
       - name: Setup julia
         uses: julia-actions/setup-julia@v1
         with: